Vast quantities of a great variety of substances are applied to plants for the purpose of enhancing the growth of the plants in order to improve the production (in the case of crop and field plants) or appearance (in the case of ornamentals) of the plants. Such substances include the group defined above as phytologically beneficial substances. It includes fertilizers, both of the macro- and micro-nutrient variety, growth stimulants or regulators, and pesticides, including fungicides, insecticides and herbicides. As used herein the word “plant” is intended to cover land and water plants, including sea plants, and “ornamentals” are intended to cover all plants that are not intended to produce a crop having economic value.
The application of phytologically beneficial substances is generally regarded as an art that is in need of improvement as a large percentage of the applied substances are not absorbed by or retained on the plants to which it is applied. Apart from the consequential wastage of expensive material and hence the unnecessary increase in production cost brought about by such wastage, the unutilized substances also give rise to pollution of the soil and water resources.
There appears to be no reference in the literature to the use of a designed biological delivery system to address the enhanced administration of specific nutrients or growth regulators to plants and/or the systemic translocation of such nutrients or growth regulators throughout the plants. It is known in the agricultural field that nutrients and other phytologically beneficial substances may be formulated with so-called chelating agents or adjuvants. Unlike the present invention the chelating agents are a clearly distinguishable group with no reference to a delivery system and are used as micro-nutrient sources that are formed by combining a chelating agent with a metal through coordinate bonding. Stability of the metal-chelate bond affects the availability to plants of the micronutrient metals—copper, iron, manganese, and zinc. An effective chelate is one in which the rate of substitution of the chelated micronutrient for other cations in the soil is quite low, thus maintaining the applied micronutrient in chelated form. Chelates are generally only applicable to cationic substances. A chelating agent, such as EDTA, is thought to have a negative impact on the environment.
According to prescriptions for chelates in the Preliminary Organic Materials List by the California Departments of Food and Agriculture, natural chelates are allowed but synthetic chelating agents are restricted for use only with micronutrient sprays for a documented deficiency. All other uses of synthetic chelates are prohibited. EDTA, lignin sulfonates and lignosulfonic acids are considered to be synthetic chelating agents. Recently, a shuttle system for the delivery of cations was announced. The shuttle system consists of long chain polysaccharides which can complex with cationic nutrients in clusters (nanoclusters), thus rendering the nutrient-chelate complex neutral. The chelators (shuttle ligand) then envelop the enclustered nutrients and shuttle them to the cell wall where they deliver their nutrients. The delivery are thought to take place through a random process whereby the pores on the plant and the shuttle ligand both contract and expand as a result of a thermal vibration, a natural phenomenon. It is thought that when contraction of the chelator and expansion of the pore synchronize, the nutrient is delivered. Upon unloading the mineral, the shuttle ligand is repulsed from the plant surface, and is attracted back to the nanocluster where it can repeat the process again and again. The shuttle chelating system may extend to other dormant cations in the soil. However, the system is still based on the use of chelates, can complex only to cationic compounds and do not penetrate the plant tissue.
Cloak Spray oil, marketed in South Africa by Nutri-Tech Solutions, is an organic blend of emulsified, cold press canola oil and omega-3 fish oil. Cloak oil is thought to be a high quality spreader, sticker synergist (see below) which is claimed to improve the performance of all foliar fertilizers. However, no claims are made regarding either the translocation of substances within the plant or the delivery of other substances or fertilization by the root system of the plant.
The most established method of introducing material or substances into plant cells is by spraying of the substance in the presence of a wetting agent, spreader or sticker. By this technique material is sprayed onto leaves of plants in the presence of a wetting agent which would cause the material to adhere to the waxy outer layer of leaves, thereby increasing contact time between the material to be absorbed by the plant and the plant leaf itself. While some of the material gets taken up, the wetting agent, which usually contains an adherent, cause the leaves to become sticky and attract dust, which in turn may lead to occlusion of the stomata. Carriers for the agricultural sector have been described but relate to methods of application and not to the enhancement of the action of the active compound due to increased delivery to the target cell or organism. The closest approximation to a delivery system that may be used to overcome barriers to entry in plants are to be found in the use of adjuvants for enhancing the activity of some active compounds in the herbicide and hormone classes.
While these techniques work adequately in the appropriate environment on some compounds that are easily absorbed by leaves, they are not regarded as being generally suitable for the effective delivery of a number of macro- and micro-nutrients, as well as a large number of pesticides and growth regulators. There has thus been a long-felt need for an appropriate process by which compounds may be introduced selectively into plant cells there to enhance growth or to treat plant diseases or deficiencies.
Adjuvants are chemically and biologically active (not chemically inert) compounds and may be classified according to their function (activator or utility), their chemistry (such as organosilicones), or source (vegetable or petroleum oils). They produce pronounced effects. Most adjuvants are incompatible with some materials and conditions and may result in toxic effects in plants and animals, and some adjuvants have the potential to be mobile and pollute surface or groundwater sources. The use of adjuvants may be problematic near water, as adverse effects may occur in some aquatic species.